This patch will parse kernel's btf data. The data can be located via __start_BTF and __stop_BTF symbols which have been resolved by kallsyms of the previous patch.
The btf data is organized as follows: each one of kernel modules, including vmlinux itself, will have a btf_file struct describing its btf data, and holding an array of struct name_entry. By given the btf type id, we can resolve its name_entry fast by array index. In addition, name_entry can also be organized in hash table. So given a type name, we can also resolve its name_entry in a fast speed. In other words, both btf type id and btf type name can we get it resolved fast. Once we get the name_entry structure of the btf type, we can resolve its member/size etc easily. Since all name_entry array starting from index 0, which cannot identify a btf type globally. So a uniq id is used, its value is accumulated by the location of the btf_file within btf_file_array and total quantity of btf types within each btf_file. Signed-off-by: Tao Liu <[email protected]> --- Makefile | 2 +- btf.c | 798 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ btf.h | 175 ++++++++++++ 3 files changed, 974 insertions(+), 1 deletion(-) create mode 100644 btf.c create mode 100644 btf.h diff --git a/Makefile b/Makefile index 2bb17f9..fbc9f5b 100644 --- a/Makefile +++ b/Makefile @@ -45,7 +45,7 @@ CFLAGS_ARCH += -m32 endif SRC_BASE = makedumpfile.c makedumpfile.h diskdump_mod.h sadump_mod.h sadump_info.h -SRC_PART = print_info.c dwarf_info.c elf_info.c erase_info.c sadump_info.c cache.c tools.c printk.c detect_cycle.c kallsyms.c +SRC_PART = print_info.c dwarf_info.c elf_info.c erase_info.c sadump_info.c cache.c tools.c printk.c detect_cycle.c kallsyms.c btf.c OBJ_PART=$(patsubst %.c,%.o,$(SRC_PART)) SRC_ARCH = arch/arm.c arch/arm64.c arch/x86.c arch/x86_64.c arch/ia64.c arch/ppc64.c arch/s390x.c arch/ppc.c arch/sparc64.c arch/mips64.c arch/loongarch64.c arch/riscv64.c OBJ_ARCH=$(patsubst %.c,%.o,$(SRC_ARCH)) diff --git a/btf.c b/btf.c new file mode 100644 index 0000000..ba376cf --- /dev/null +++ b/btf.c @@ -0,0 +1,775 @@ +#include "btf.h" +#include <stdio.h> +#include <assert.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <libelf.h> +#include <gelf.h> +#include <dirent.h> +#include "kallsyms.h" +#include "makedumpfile.h" + +// btf_files_array[0] must be kernel itself +// btf_files_array[1..] are kernel modules +static struct btf_file **btf_files_array = NULL; +static int btf_files_array_index = 0; + +static inline uint16_t btf_vlen(uint32_t info) +{ + return info & 0xFFFF; +} + +static inline uint32_t btf_kind_flag(uint32_t info) +{ + return info & (1 << 31); +} + +static inline uint32_t btf_member_bit_offset(uint32_t value) +{ + return value & 0xffffff; +} + +static inline uint32_t btf_member_bitfield_size(uint32_t value) +{ + return value >> 24; +} + +static struct btf_type *btf_next(struct btf_type *tp) +{ + uintptr_t next = (uintptr_t)&tp[1]; + + switch (btf_kind(tp->info)) { + case BTF_KIND_INT: + next += sizeof(uint32_t); + break; + + case BTF_KIND_ARRAY: + next += sizeof(struct btf_array); + break; + + case BTF_KIND_STRUCT: + case BTF_KIND_UNION: + next += btf_vlen(tp->info) * sizeof(struct btf_member); + break; + + case BTF_KIND_ENUM: + next += btf_vlen(tp->info) * sizeof(struct btf_enum); + break; + + case BTF_KIND_FUNC_PROTO: + next += btf_vlen(tp->info) * sizeof(struct btf_param); + break; + + case BTF_KIND_VAR: + next += sizeof(struct btf_var); + break; + + case BTF_KIND_DATASEC: + next += btf_vlen(tp->info) * sizeof(struct btf_var_secinfo); + break; + + case BTF_KIND_DECL_TAG: + next += sizeof(struct btf_decl_tag); + break; + + case BTF_KIND_ENUM64: + next += btf_vlen(tp->info) * sizeof(struct btf_enum64); + break; + + case BTF_KIND_PTR: + case BTF_KIND_FWD: + case BTF_KIND_TYPEDEF: + case BTF_KIND_VOLATILE: + case BTF_KIND_CONST: + case BTF_KIND_RESTRICT: + case BTF_KIND_FUNC: + case BTF_KIND_FLOAT: + case BTF_KIND_TYPE_TAG: + break; // no extra data + + default: + __builtin_unreachable(); + } + return (struct btf_type *)next; +} + +#define NAME_HASH 512 +static struct name_entry *name_hash_table[NAME_HASH] = {0}; + +static void *get_name_entry_next(void *entry) +{ + return ((struct name_entry *)entry)->name_hash_next; +} + +static void set_name_entry_next(void *entry, void *next) +{ + ((struct name_entry *)entry)->name_hash_next = next; +} + +static void name_hash_install(struct name_entry *en) +{ + hash_install((void **)name_hash_table, NAME_HASH, en, en->name, + get_name_entry_next, set_name_entry_next); +} + +static unsigned int name_hash_index(char *name) +{ + return hash_index(name, NAME_HASH); +} + +int read_file_at_offset(char *f, int f_off, int r_size, void *buf) +{ + int got = 0; + int r, fd, ret = -1; + + fd = open(f, O_RDONLY); + if (fd < 0) { + fprintf(stderr, "%s: Failed to open file %s\n", __func__, f); + goto out; + } + + while (got < r_size) { + r = pread(fd, buf + got, r_size - got, f_off + got); + if (r < 0) { + fprintf(stderr, "%s: Failed to read file %s\n", __func__, f); + goto clean_fd; + } + got += r; + } + ret = got; + +clean_fd: + close(fd); +out: + return ret; +} + +static char *get_str_by_name_off(struct btf_file *bf, uint32_t name_off) +{ + struct btf_file *bf_vmlinux = btf_files_array[0]; + + if (bf != bf_vmlinux && name_off >= bf_vmlinux->str_cache_len) + return bf->str_cache + name_off - bf_vmlinux->str_cache_len; + else + return bf_vmlinux->str_cache + name_off; +} + +int get_btf_type_by_type_id(struct btf_file *bf_in, uint32_t id_in, + struct btf_type *bt_out, struct name_entry **en_out) +{ + struct name_entry *en; + struct btf_file *bf_vmlinux = btf_files_array[0]; + + if (bf_in != bf_vmlinux && id_in > bf_vmlinux->array_len) { + en = bf_in->array[id_in - bf_vmlinux->array_len - 1]; + } else { + en = bf_vmlinux->array[id_in - 1]; + } + if (en_out) + *en_out = en; + return read_file_at_offset(en->bf->file_name, + en->btf_type_offset + en->bf->types_data_offset, + sizeof(*bt_out), bt_out); +} + +/* +* Parse the btf data and install elements into hashtable and array for quick +* reference. +*/ +static int parse_btf_data(char *file_path, char *data_start, uint32_t data_len) +{ + struct btf_header *hdr = (struct btf_header *)data_start; + struct btf_file *bf = NULL; + void *type_start; + char *str_start; + struct btf_type *tp; + struct name_entry *en; + int i, j, scale; + + /* We do some check first */ + if (hdr->magic != BTF_MAGIC) { + fprintf(stderr, "%s: Invalid BTF magic in %s\n", + __func__, file_path); + goto out; + } + if (hdr->hdr_len != sizeof(*hdr)) { + fprintf(stderr, "%s: Invalid BTF header length in %s\n", + __func__, file_path); + goto out; + } + if (hdr->hdr_len + hdr->str_off + hdr->str_len > data_len) { + fprintf(stderr, "%s: String section exceeds data length in %s\n", + __func__, file_path); + goto out; + } + if (hdr->hdr_len + hdr->type_off + hdr->type_len > data_len) { + fprintf(stderr, "%s: Type section exceeds data length in %s\n", + __func__, file_path); + goto out; + } + + /* Let's start parsing */ + bf = (struct btf_file *)malloc(sizeof(*bf)); + if (!bf) + goto no_mem; + memset(bf, 0, sizeof(*bf)); + + /* Enlarge array when reach power of 2 */ + btf_files_array[btf_files_array_index++] = bf; + if ((btf_files_array_index & (btf_files_array_index - 1)) == 0) { + struct btf_file **tmp = (struct btf_file **)reallocarray(btf_files_array, + btf_files_array_index << 1, + sizeof(struct btf_file *)); + if (!tmp) + goto no_mem; + btf_files_array = tmp; + } + + type_start = data_start + hdr->hdr_len + hdr->type_off; + str_start = data_start + hdr->hdr_len + hdr->str_off; + + bf->str_cache = malloc(hdr->str_len); + if (!bf->str_cache) + goto no_mem; + memcpy(bf->str_cache, str_start, hdr->str_len); + bf->str_cache_len = hdr->str_len; + + bf->array_len = 64; + bf->array = (struct name_entry **)calloc(bf->array_len, + sizeof(struct name_entry *)); + if (!bf->array) + goto no_mem; + + bf->file_name = strdup(file_path); + if (!bf->file_name) + goto no_mem; + bf->types_data_offset = (char *)type_start - data_start; + + for (tp = (struct btf_type *)type_start, i = 0; + (void *)tp < type_start + hdr->type_len; + tp = btf_next(tp), i++) { + en = (struct name_entry *)malloc(sizeof(struct name_entry)); + if (!en) { + bf->array_len = i; + goto no_mem; + } + memset(en, 0, sizeof(struct name_entry)); + + en->btf_type_offset = (void *)tp - type_start; + en->id = i + 1; + en->bf = bf; + if (tp->name_off) { + en->name = get_str_by_name_off(bf, tp->name_off); + if (en->name[0]) + name_hash_install(en); + } + bf->array[i] = en; + + /* Now deal with sub elements which also have a name */ + if (btf_kind(tp->info) == BTF_KIND_ENUM || + btf_kind(tp->info) == BTF_KIND_ENUM64) { + scale = btf_kind(tp->info) == BTF_KIND_ENUM ? + sizeof(struct btf_enum) : sizeof(struct btf_enum64); + for (j = 0; j < btf_vlen(tp->info); j++) { + en = (struct name_entry *)malloc(sizeof(struct name_entry)); + if (!en) { + bf->array_len = i + 1; + goto no_mem; + } + memset(en, 0, sizeof(struct name_entry)); + en->id = 0; + en->p_id = i + 1; + en->p_id += btf_files_array_index == 1 ? + 0 : btf_files_array[0]->array_len; + en->bf = bf; + en->name = get_str_by_name_off(bf, + *(uint32_t *)((char *)&tp[1] + j * scale)); + // printf("%s\n", en->name); + name_hash_install(en); + } + } + + /* Enlarge array when over 3/4 */ + if (i > (bf->array_len >> 2) * 3) { + struct name_entry **tmp = (struct name_entry **)reallocarray(bf->array, + bf->array_len << 1, sizeof(struct name_entry *)); + if (!tmp) + goto no_mem; + bf->array = tmp; + bf->array_len <<= 1; + } + } + bf->array_len = i; + return 0; +no_mem: + /* All the memory free will be dealed later. */ + fprintf(stderr, "%s: Not enough memory!\n", __func__); +out: + return -1; +} + +/* + * Used by search_name_by_cond() for searching specific type: + * such as struct/union/typedef + */ +static bool is_type(struct name_entry *sp, void *data_in, void *data_out) +{ + struct btf_type *bt = (struct btf_type *)data_out; + int type = *(int *)data_in; + if (sp->id) { + read_file_at_offset(sp->bf->file_name, + sp->btf_type_offset + sp->bf->types_data_offset, + sizeof(*bt), bt); + return btf_kind(bt->info) == type; + } + return false; +} + +static struct name_entry *search_name_by_cond(char *name, + bool (*fn)(struct name_entry *, void *, void *), + void *data_in, void *data_out) +{ + unsigned int index; + struct name_entry *sp; + + index = name_hash_index(name); + for (sp = name_hash_table[index]; sp; sp = sp->name_hash_next) { + if (!strcmp(name, sp->name) && fn(sp, data_in, data_out)) { + return sp; + } + } + return sp; +} + +// caller should prepare bt +void resolve_typedef(struct name_entry *en_in, struct name_entry **en_out, + struct btf_type *bt) +{ + uint32_t id; + struct name_entry *en; + + read_file_at_offset(en_in->bf->file_name, + en_in->btf_type_offset + en_in->bf->types_data_offset, + sizeof(*bt), bt); + if (btf_kind(bt->info) == BTF_KIND_TYPEDEF) { + id = bt->type; + get_btf_type_by_type_id(en_in->bf, id, bt, &en); + return resolve_typedef(en, en_out, bt); + } else { + *en_out = en_in; + } +} + +struct cond_args { + int index; + char *name; +}; + +static bool cond(struct cond_args *c1, struct cond_args *c2) +{ + if (c1->name && c2->name) + /* Check if the member name is what we want */ + return !strcmp(c1->name, c2->name); + else + /* Check if the member index is what we want */ + return c1->index == c2->index; +} + +static bool get_internal_member_info(struct name_entry *en, int base_position, + int *global_index, struct cond_args *tar_arg, + struct member_info *mi, bool initial_dive) +{ + struct btf_type bt, sub_bt; + int member_num; + char *member_array_buf = NULL; + int i; + struct btf_member *bm; + struct btf_array *ba; + int bm_position; + struct name_entry *sub_en; + bool res; + struct cond_args cur_arg = {0}; + + read_file_at_offset(en->bf->file_name, + en->btf_type_offset + en->bf->types_data_offset, + sizeof(bt), &bt); // this struct + if (initial_dive || + ((!en->name || en->name[0] == '\0') && + ((btf_kind(bt.info) == BTF_KIND_STRUCT) || + (btf_kind(bt.info) == BTF_KIND_UNION)))) { + /* anonymous struct/union, dive into */ + member_num = btf_vlen(bt.info); + member_array_buf = calloc(member_num, sizeof(struct btf_member)); + if (!member_array_buf) { + fprintf(stderr, "%s: Not enough memory!\n", __func__); + return false; + } + read_file_at_offset(en->bf->file_name, + en->btf_type_offset + en->bf->types_data_offset + sizeof(bt), + member_num *sizeof(struct btf_member), member_array_buf); + for (i = 0, bm = (struct btf_member *)member_array_buf; + i < member_num; i++) { + if (btf_kind_flag(bt.info)) { + bm_position = base_position + + btf_member_bit_offset(bm[i].offset); + mi->bits = btf_member_bitfield_size(bm[i].offset); + } else { + bm_position = base_position + + bm[i].offset; + } + mi->sname = get_str_by_name_off(en->bf, bm[i].name_off); + get_btf_type_by_type_id(en->bf, bm[i].type, + &sub_bt, &sub_en); + // Dive into this member + res = get_internal_member_info(sub_en, bm_position, global_index, + tar_arg, mi, false); + if (res) { + free(member_array_buf); + return res; + } + } + free(member_array_buf); + return false; + } + + cur_arg.index = *global_index; + cur_arg.name = mi->sname; + if (cond(&cur_arg, tar_arg)) { + mi->bit_pos = base_position; + resolve_typedef(en, &sub_en, &bt); + mi->uniq_id = id_to_uniq_id(sub_en->id, sub_en->bf); + if (btf_kind(bt.info) == BTF_KIND_PTR) { + /* + * BUG? No pointer size in btf, + * 32bit btf target on 64bit machine + */ + mi->size = sizeof(void *); + mi->type = "char *"; + } else if (btf_kind(bt.info) == BTF_KIND_ARRAY) { + en = sub_en; + ba = (struct btf_array *)malloc(sizeof(struct btf_array)); + if (!ba) { + fprintf(stderr, "%s: Not enough memory!\n", __func__); + return false; + } + read_file_at_offset(en->bf->file_name, + en->btf_type_offset + en->bf->types_data_offset + sizeof(bt), + sizeof(struct btf_array), ba); + mi->size = ba->nelems; // array elements + get_btf_type_by_type_id(en->bf, ba->type, &sub_bt, &sub_en); + resolve_typedef(sub_en, &en, &bt); + free(ba); + mi->size *= bt.size; // element size + mi->type = NULL; // "char [64]? Leave it NULL for now" + } else { + mi->size = bt.size; + mi->type = get_str_by_name_off(sub_en->bf, bt.name_off); + } + return true; + } else { + (*global_index)++; + return false; + } +} + +static bool get_member_info_by_index(struct name_entry *en, int target_index, + struct member_info *mi) +{ + int g_index = 1; + struct cond_args args = {0}; + args.index = target_index; + memset(mi, 0, sizeof(*mi)); + return get_internal_member_info(en, 0, &g_index, &args, mi, true); +} + +static bool get_member_info_by_member_name(struct name_entry *en, char *member_name, + struct member_info *mi) +{ + int g_index = 1; + struct cond_args args = {0}; + args.name = member_name; + memset(mi, 0, sizeof(*mi)); + return get_internal_member_info(en, 0, &g_index, &args, mi, true); +} + +/* + * Entry for query struct members + * Return: struct size, mi_out: member details + */ +uint32_t get_struct_member_by_name(char *struct_name, char *member_name, + struct member_info *mi_out) +{ + struct name_entry *en; + struct btf_type bt = {0}; + int type = BTF_KIND_STRUCT; + + en = search_name_by_cond(struct_name, is_type, (void *)&type, (void *)&bt); + if (!en) + goto out; + if (get_member_info_by_member_name(en, member_name, mi_out)) + return bt.size; +out: + return 0; +} + +/* + * Entry for query type members, similar as above + * Return: found-the-type, mi_out: member details + */ +static uint32_t uniq_id_to_id(uint32_t, struct btf_file **); +bool get_type_member_by_index(uint64_t type_uniq_id, int member_index, + struct member_info *mi_out) +{ + uint32_t id; + struct btf_file *bf; + + id = uniq_id_to_id((uint32_t)type_uniq_id, &bf); + return get_member_info_by_index(bf->array[id - 1], member_index, mi_out); +} + +uint32_t id_to_uniq_id(uint32_t id, struct btf_file *bf) +{ + int i; + uint32_t uniq_id = 0; + for (i = 0; i < btf_files_array_index; i++) { + if (btf_files_array[i] != bf) + uniq_id += btf_files_array[i]->array_len; + else + return id + uniq_id; + } + __builtin_unreachable(); + assert(false); +} + +static uint32_t uniq_id_to_id(uint32_t uid, struct btf_file **bf) +{ + int i; + + for (i = 0; i < btf_files_array_index; i++) { + if (uid > btf_files_array[i]->array_len) { + uid -= btf_files_array[i]->array_len; + } else { + if (bf) + *bf = btf_files_array[i]; + return uid; + } + + } + __builtin_unreachable(); + assert(false); +} + +// api for eppic +uint32_t get_type_size_by_name(char *type_name, int type, uint32_t *uniq_id) +{ + struct name_entry *en; + struct btf_type bt = {0}; + + en = search_name_by_cond(type_name, is_type, (void *)&type, (void *)&bt); + if (!en) + goto out; + if (uniq_id) + *uniq_id = id_to_uniq_id(en->id, en->bf); + return bt.size; +out: + return 0; +} + +// Caller should prepare bt_out +struct name_entry *get_en_by_uniq_id(uint32_t uniq_id, struct btf_type *bt_out) +{ + uint32_t id; + struct btf_file *bf; + struct name_entry *en; + struct name_entry *en_sub; + + id = uniq_id_to_id((uint32_t)uniq_id, &bf); + en = bf->array[id - 1]; + resolve_typedef(en, &en_sub, bt_out); + return en_sub; +} + +/* Deal with btf file */ +static int btf_file_init(int fd) +{ + struct stat f_stat; + char *buf = NULL; + char proc_path[32]; + char real_path[512]; + int ret = -1; + + memset(real_path, 0, sizeof(real_path)); + if (fstat(fd, &f_stat) < 0) { + fprintf(stderr, "%s: fstat fail!\n", __func__); + goto out; + } + buf = malloc(f_stat.st_size); + if (!buf) { + fprintf(stderr, "%s: Not enough memory!\n", __func__); + goto out; + } + + snprintf(proc_path, sizeof(proc_path), "/proc/self/fd/%d", fd); + readlink(proc_path, real_path, sizeof(real_path) - 1); + if (read_file_at_offset(real_path, 0, f_stat.st_size, buf) < 0) + goto out; + + ret = parse_btf_data(real_path, buf, f_stat.st_size); +out: + if (buf) + free(buf); + return ret; +} + +/* Deal with elf file which contains .BTF section */ +static int elf_file_init(int fd) +{ + char proc_path[32]; + char real_path[512]; + Elf *elf = NULL; + Elf_Scn *scn = NULL; + size_t shstrndx; + GElf_Shdr shdr; + Elf_Data *data = NULL; + char *str, *databuf = NULL; + int ret = -1; + + snprintf(proc_path, sizeof(proc_path), "/proc/self/fd/%d", fd); + readlink(proc_path, real_path, sizeof(real_path) - 1); + + if (elf_version(EV_CURRENT) == EV_NONE) + goto elf_err; + elf = elf_begin(fd, ELF_C_READ, NULL); + if (!elf || elf_getshdrstrndx(elf, &shstrndx)) + goto elf_err; + while ((scn = elf_nextscn(elf, scn)) != NULL) { + if (!gelf_getshdr(scn, &shdr)) + continue; + str = elf_strptr(elf, shstrndx, shdr.sh_name); + if (!strcmp(str, ".BTF")) + break; + } + if (!scn) { + fprintf(stderr, "%s: No .BTF found in %s!\n", __func__, real_path); + goto out; + } + + data = elf_rawdata(scn, data); + databuf = malloc(data->d_size); + if (!databuf) { + fprintf(stderr, "%s: Not enough memory!\n", __func__); + goto out; + } + memcpy(databuf, data->d_buf, data->d_size); + elf_end(elf); + elf = NULL; + ret = parse_btf_data(real_path, databuf, data->d_size); + goto out; + +elf_err: + fprintf(stderr, "%s: elf error in %s!\n", __func__, real_path); +out: + if (databuf) + free(databuf); + if (elf) + elf_end(elf); + return ret; +} + +/* + * Entry for parse btf file and elf file. + */ +static int file_init(char *name) +{ + int fd = 0, ret = -1; + char buf[4] = {0}; + + /* Will be enlarged automatically */ + if (!btf_files_array) { + btf_files_array = calloc(1, sizeof(struct btf_file *)); + if (!btf_files_array) { + fprintf(stderr, "%s: Not enough memory!\n", __func__); + goto out; + } + } + + fd = open(name, O_RDONLY); + if (read_file_at_offset(name, 0, sizeof(buf), buf) < 0) + goto out; + if (*(u_int16_t *)&buf == BTF_MAGIC) { + ret = btf_file_init(fd); + } else if (*(u_int32_t *)&buf == (((u_int32_t)ELFMAG0 << 24) | + ((u_int32_t)ELFMAG1 << 16) | + ((u_int32_t)ELFMAG2 << 8) | + ((u_int32_t)ELFMAG3 << 0))) { + ret = elf_file_init(fd); + } else { + __builtin_unreachable(); + } + +out: + if (fd) + close(fd); + return ret; +} + +/* For pure buffer data, wrap it as a file, and handover to file_init() */ +char temp[] = "/tmp/btf_XXXXXX"; +static int init_btf_from_buf(char *mod_name, char *buf, int size) +{ + int fd; + char name_buf[64]; + int w, got = 0; + static char *temp_dir = NULL; + + if (!temp_dir) + temp_dir = mkdtemp(temp); + snprintf(name_buf, sizeof(name_buf), "%s/%s", temp_dir, mod_name); + fd = open(name_buf, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR); + if (fd < 0) { + fprintf(stderr, "%s: open fail in %s!\n", __func__, name_buf); + return -1; + } + + while (got < size) { + w = pwrite(fd, buf + got, size - got, got); + if (w < 0) { + fprintf(stderr, "%s: pwrite fail in %s!\n", __func__, name_buf); + return -1; + } + got += w; + } + close(fd); + return file_init(name_buf); +} + +int init_kernel_btf(void) +{ + uint64_t size; + char *buf; + int ret; + + uint64_t start_btf = get_kallsyms_value_by_name("__start_BTF"); + uint64_t stop_btf = get_kallsyms_value_by_name("__stop_BTF"); + if (!start_btf || !stop_btf) { + fprintf(stderr, "%s: symbol __start/stop_BTF not found!\n", __func__); + return -1; + } + + size = stop_btf - start_btf; + buf = (char *)malloc(size); + if (!buf) { + fprintf(stderr, "%s: Not enough memory!\n", __func__); + return -1; + } + readmem(VADDR, start_btf, buf, size); + ret = init_btf_from_buf("vmlinux", buf, size); + free(buf); + + return ret; +} + diff --git a/btf.h b/btf.h new file mode 100644 index 0000000..424e9e0 --- /dev/null +++ b/btf.h @@ -0,0 +1,175 @@ +#ifndef _BTF_H +#define _BTF_H +#include <stdint.h> +#include <stdbool.h> + +typedef uint8_t __u8; +typedef uint16_t __u16; +typedef uint32_t __u32; +typedef int32_t __s32; + +#define BTF_MAGIC 0xeb9f + +enum { + BTF_KIND_UNKN = 0, /* Unknown */ + BTF_KIND_INT = 1, /* Integer */ + BTF_KIND_PTR = 2, /* Pointer */ + BTF_KIND_ARRAY = 3, /* Array */ + BTF_KIND_STRUCT = 4, /* Struct */ + BTF_KIND_UNION = 5, /* Union */ + BTF_KIND_ENUM = 6, /* Enumeration */ + BTF_KIND_FWD = 7, /* Forward */ + BTF_KIND_TYPEDEF = 8, /* Typedef */ + BTF_KIND_VOLATILE = 9, /* Volatile */ + BTF_KIND_CONST = 10, /* Const */ + BTF_KIND_RESTRICT = 11, /* Restrict */ + BTF_KIND_FUNC = 12, /* Function */ + BTF_KIND_FUNC_PROTO = 13, /* Function Proto */ + BTF_KIND_VAR = 14, /* Variable */ + BTF_KIND_DATASEC = 15, /* Section */ + BTF_KIND_FLOAT = 16, /* Floating point */ + BTF_KIND_DECL_TAG = 17, /* Decl Tag */ + BTF_KIND_TYPE_TAG = 18, /* Type Tag */ + BTF_KIND_ENUM64 = 19, /* Enumeration up to 64-bit values */ + + NR_BTF_KINDS, + BTF_KIND_MAX = NR_BTF_KINDS - 1, +}; + +struct btf_type { + __u32 name_off; + + /* "info" bits arrangement + * bits 0-15: vlen (e.g. # of struct's members) + * bits 16-23: unused + * bits 24-27: kind (e.g. int, ptr, array...etc) + * bits 28-30: unused + * bit 31: kind_flag, currently used by + * struct, union and fwd + */ + __u32 info; + + /* "size" is used by INT, ENUM, STRUCT, UNION and DATASEC. + * "size" tells the size of the type it is describing. + * + * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT, + * FUNC, FUNC_PROTO, VAR, DECL_TAG and TYPE_TAG. + * "type" is a type_id referring to another type. + */ + union { + __u32 size; + __u32 type; + }; +}; + +struct btf_header { + __u16 magic; + __u8 version; + __u8 flags; + __u32 hdr_len; + + /* All offsets are in bytes relative to the end of this header */ + __u32 type_off; /* offset of type section */ + __u32 type_len; /* length of type section */ + __u32 str_off; /* offset of string section */ + __u32 str_len; /* length of string section */ +}; + +struct btf_array { + __u32 type; + __u32 index_type; + __u32 nelems; +}; + +struct btf_member { + __u32 name_off; + __u32 type; + /* If the type info kind_flag is set, the btf_member offset + * contains both member bitfield size and bit offset. The + * bitfield size is set for bitfield members. If the type + * info kind_flag is not set, the offset contains only bit + * offset. + */ + __u32 offset; +}; + +struct btf_enum { + __u32 name_off; + __s32 val; +}; + +struct btf_enum64 { + __u32 name_off; + __u32 val_lo32; + __u32 val_hi32; +}; + +struct btf_param { + __u32 name_off; + __u32 type; +}; + +struct btf_var { + __u32 linkage; +}; + +struct btf_var_secinfo { + __u32 type; + __u32 offset; + __u32 size; +}; + +struct btf_decl_tag { + __s32 component_idx; +}; + +/*************************************/ +struct btf_file { + char *file_name; + char *str_cache; + uint32_t str_cache_len; + uint32_t types_data_offset; + uint32_t array_len; + struct name_entry **array; +}; + +struct name_entry { + union { + uint32_t btf_type_offset; + uint32_t p_id; + }; + + uint32_t id; + char *name; + struct btf_file *bf; + struct name_entry *name_hash_next; +}; + +struct member_info { + char *sname; // member name + char *type; // member type: int, long etc + uint32_t bit_pos; // member position in bits + uint32_t bits; // member width in bits + uint32_t size; // member size in bytes + int uniq_id; // uniq_id of btf +}; + +/*************************************/ + +int read_file_at_offset(char *, int, int, void *); +int init_kernel_btf(void); +uint32_t get_struct_member_by_name(char *, char *, struct member_info *); +bool get_type_member_by_index(uint64_t, int, struct member_info *); +uint32_t get_type_size_by_name(char *, int, uint32_t *); +struct name_entry *get_en_by_uniq_id(uint32_t, struct btf_type *); +void resolve_typedef(struct name_entry *, struct name_entry **, struct btf_type *); +int get_btf_type_by_type_id(struct btf_file *, uint32_t, + struct btf_type *, struct name_entry **); +uint32_t id_to_uniq_id(uint32_t, struct btf_file *); + +static inline uint32_t btf_kind(uint32_t info) +{ + return (info & 0x1F000000) >> 24; +} + +#endif /* _BTF_H */ -- 2.47.0
